In the fourth century Christian monasticism left the anchoritic lifestyle to begin a new monastic organization. These religious communities not only show us an architecture ruled by a monastic life, but also reveals some impressive hydraulic systems occasionally reflected in valuable drawings.

From the first graphic document of Saint-Gall abbey, until the parchment of the Corb River (exclusively photographed at the scriptorium of Vallbona monastery), this work demonstrates that graphic representation of water supply systems has played a very important role throughout time.

Thanks to these graphic documents we can currently know about other important aspects such as irrigation rights, water supply channels, hydraulic systems to pump water, etc. All these elements have become the only witnesses of an invisible architecture located under the ground, which has almost disappeared nowadays.